The present invention relates to a method for setting torque during the operation of a motor vehicle.
The torque of an internal combustion engine in a motor vehicle is usually selected by the driver, using the accelerator pedal for the driver-selected torque. In this connection, it has turned out, especially in the case of small accelerator pedal deliveries in the lower to medium load range, that the result is a relatively sluggish reaction, above all in the case of relatively weakly performing, low-volume internal combustion engines. That is explained by the fact that the small accelerator pedal delivery is equivalent to a small engine torque increase. Correspondingly, the throttle moves by only a relatively small angle, whereby the change in engine torque is dynamically set relatively slow, since the cylinder charge is usually throttled dynamically. The responsiveness of a vehicle is customarily set by the characteristics of the accelerator pedal. In this connection, there is the problem that these characteristics have the same effect when parking and leaving a parking space as they do in the case of acceleration processes. In the case of parking and leaving a parking space, fine dosing is required, whereas otherwise a responsive access characteristic is desirable, i.e., the driver expects an immediate engine response to his accelerator change. This conflict of aims between responsiveness and dosability is set in motor vehicles as a compromise in the characteristics of the acceleration pedal.
It is an object of the present invention to provide a method by which an improved responsiveness of the motor vehicle is achieved even in the lower and medium load range at small accelerator pedal deliveries.
The above and other beneficial objects of the present invention are achieved by providing a method as described herein.
According to the present invention, the driver-selected torque is dynamically magnified in time, so that the actual value of the torque approaches the setpoint value faster; which the driver experiences as improvement in responsiveness. The subsequent reduction in the enhancement component at the approach of the actual value of the torque to the driver-selected torque down to an enhancement component of zero has the effect of a gentle approach to the setpoint value, and prevents an overshooting engine torque.
The reduction of the enhancement component may occur as a function of the difference between the actual value of the torque and the driver-selected torque, so that the enhancement component automatically tends to zero when this difference tends to zero.
The enhancement component may be formed with the aid of a multiplication factor, especially a parameter-dependent multiplication factor. Such parameters are, for example, the current gear step of the transmission and/or the intake temperature and/or the engine speed and/or an ambient correction factor and/or the vehicle type in question. The setpoint selection may then be made with the aid of a characteristics map.
In one example embodiment of the method according to the present invention, the difference value between the actual value of the torque and the driver-selected torque has the multiplication factor applied to it, and the value thus obtained is added to the driver-selected torque for achieving a magnified torque value. It is achieved thereby that the enhancement component is reduced proportionally to the difference value, and thus leads to a gentle feedback to the driver-selected torque or the driver setpoint torque, respectively.
The magnification may be limited to that time interval during which the actual engine torque is less than the driver-selected torque. The torque magnification may be shut off below a specifiable speed, in order to remove, for example, for procedures in connection with parking and leaving parking spaces, the otherwise desired responsive and dynamic response characteristics.
For performing the method, a microcomputer may be provided, which may be, for example, the microcomputer in the central vehicle electronics, which is present anyway.
One example embodiment of the present invention is illustrated in the drawing and explained in detail below.